1. Technical Field
This invention relates to antenna systems and, more particularly, to a cavity-backed slot antenna having a wide operating frequency bandwidth and dual resonant frequency capabilities.
2. Discussion
Low profile conformal antennas have become particularly useful for transmit and receive systems such as advanced identification of friend or foe (AIFF) and satellite communication systems. These systems typically employ very close transmit and receive frequencies. Conventional slot antennas and printed microstrip patch antennas have been developed and used for such applications. However, these conventional antennas generally operate at a very narrow frequency bandwidth or employ a multi-resonant frequency design with a relatively wide separation in frequency.
Parasitic horizontally and stack vertically antenna systems have been used to broaden the frequency bandwidth. However, these types of parasitic antennas generally require an increase in either aperture size or thickness. In addition, when employed for multi-mode multi-resonant applications, conventional parasitic antennas are usually less efficient and generally have wider resonant frequency separations.
A conventional cavity backed dielectric loaded printed circuit slot antenna generally includes a slot etched within a single conductive cavity. Such a convention single cavity-backed slot antenna is typically limited to a relatively very narrow frequency bandwidth. Hence, in order to make the conventional single cavity-backed slot antenna more useful for applications which require a wider frequency range, the frequency bandwidth would need to be broadened or a dual resonant frequency employed.
It is therefore desirable to obtain a cavity-backed slot antenna having a relatively wide operating frequency bandwidth and dual resonant frequency capabilities. It is further desirable to have such a cavity-backed slot antenna which does not require an increase in the antenna aperture and thickness and yet substantially maintains the radiation efficiency of a similar size single cavity slot antenna.